Air preheating apparatus



.AIR FREHEATING APPARATUS Y Filed may 2e, 1938 v 3 sheetssheet 1 fm1 g :im XN, l 13g/4;; M i

INVENTOR G'er/Mr//Vz'e//l/fz Wa@ ATTORNEY Sept. 3,v v1940.rv 3. NIEMrrz r AIR PREHEATNG APPARATUS Filed May 26, 1938 NVENTOR I5 Sheets-#Sheet 2 BY I 'ATTORNEY Sept. 3, 1940.

G. NIEMITZ AIR FREHEATING APPARATUS Filed lay 26, 1958 3 Sheets-Sheet nwENToR Cfr/mrd /V/em/ f2 ATTORNEY Patented Sept. 3, 1940 PATENT OFFICE VAIR, PREHEATING APPARATUS Gerhard Niemitz, NewYork, N. Y., assigner, by

mesne assignments,

to Kennedy-Van Saun Mfg. & Eng. Corporation, New York, N. Y., a

` corporation'of Delaware A Application May 26, 1938, Serial No. 210,149

9 Claims.

heat of a heated uid such as the waste gases orv products ofcombustion of a boiler furnace or kiln, and the preheated airmixed with and constituting a part of a fluent fuel, such as pulverized coal, or delivered to the -pulverizing chamberY of Va coal pulveriam to absorb the moisture content and dry the coal as it is pulverizecl and mixed withr the pulverized coal to serve as the conveying vehicle therefor and comprisev a com.- bustible fuel, or the .preheated air delivered to the place of combustion of fuel to constitute a secondary air supply to be mixed with the fuel during the combustion thereof.

Air preheaters of this character comprise a casing arranged with a chamber at one end having anl inlet for the passage of the waste gases or products of combustion, a chamber at the opposite end having an outlet for the gases adapted to be connected to a stack, and a chamber intermediate said inlet andoutlet chambers having ducts in the form of tubes extended therethrough and fixed at\-the opposite ends in openings in the separating walls for the passage of the waste gases or products of combustion, the intermediate chamber also having an air inlet to one end and a side thereof, and an outlet from the opposite end and pass through said chamber in a direction epposite to the flow of the gases through'the duets andvtraverse saidfducts in the passage of the ai;v through the chamber to transfer the heat of the gases to the air.

In the use of the apparatus in connection with a coal fired boiler furnace the intermediate heat transfer chamber of thevapparatus is of a capacity and provided with a number of ducts so that the apparatus will operate to efliciently heat a volume of air to a temperature sufficiently high to absorb the moisture content and dry the coal as it is pulverized when the boiler furnace is operating under high load, however, when the boiler furnace is operated under a low load it will not operate to heat the air to the desired and necessary t'erripe'rature for the eicient operation of the pulverizer and furnace.

Itis vthe objectvof the invention to provide an improved air heating apparatus of this character to overcome the Yabove disadvantages and opverate to heat the air to a desired temperature when the boiler furnace is operating under both -low and high loads, and to provide apparatus for thisv purpose that is simple in construction and eflicient in use.

side thereof to cause the air to' It is a further object of this invention to provide air heating apparatus of this character ineluding a casing arranged with a chamber at one end having an inlet for the waste gases of l combustion, a chamber at the opposite end hav- 5 ing an outlet for said gases and a chamber ntermediate said end chambers arranged witha series of passes open to each otherat opposite sides of the casing and said casing having an inlet and an outlet for the air to be heated in communication with said passes, and each pass arranged with aseries of ducts for the passage of the gases with'one series in communication with the gas inlet, and the provision of means tocause the gas to pass through one series of ducts or all of the series of ducts from the gas inlet to the gas outlet, and means to cause the air to pass through and traverse the ducts in one of. the passes, or pase successively through and trav-'- erse the ductsin all of the passes from the air inlet to the air outlet.

It is a furtherobject of the invention t'o provide an 'air heating apparatusV of this character vhaving multiple passes for the gases and air, and means to separate ash and other foreign substances from theY gases, and means to induce a flow of the gases through the apparatus and the connecting of said means and the separator inthe connection of the outlet for the. gases with a Y i stack.

Other objects and advantages of the invention will hereinafter appear.

In the drawings accompanying and forming a.

, part of this application,

Figure l is a longitudinal sectional view of aparatus for. heating air by waste gases of combustion and showing the same connected to a stack with a [an andseparator interposed in the connections thereof with the stack andshowing anA embodiment of the invention, the section of the air heating means being taken substantially on the linev I-l of Figure 2 looking in the-direction of the arrows, l.

Figure 2 is a longitudinal sectional view taken substantially centrally througlrthe air heating apparatus of Figure l and showing the inlet for the waste gases of combustion connected in communication with the outlet for the exitgases of a. boiler furnace,

Figure 3 ,is a cross sectional view taken sub stentially on the line 3--3 of Figure 2 looking in the direction of the arrows, and i Figure 4 is a view similar to Figure 3 on a reduced scale and showing another position of ad- 55 ing supported in vertically disposed position and `shown as arranged at the rear of a boiler furnace a part of which is shown in a general way at B in Figure 2. 'The casing comprises side walls 5, 6, end walls 1, 8, a top closurewall 9 and a bottom wall in the form of a double hopperg III, III with the side wall terminating in spaced relation to one wall of the hopper III providing opening consisting in eiect a continuation of the outlet pass for the exit ofthe waste gases or products of combustionl from the boiler furnace, said gases passing into the hopperbottom in the direction indicated by the arrows a. A partition II extending transversely of the casing adjacent to but spaced from the hopper bottom provides a chamber between said partition and the hopper bottom separated by a vertical wall I2 into two portions C and C with the inlet for the hot gases of combustion to the portion C. A partition I3 extending transversely of the casing adjacent to and spaced from the top closure l provides a chamber C2 for the gases having an outlet Il at one end thereof. The partitions Il, I3 arrange the casing with a chamber intermediate 'the chambers C, C' and C, said chamber being provided with a series oi passes for the air, shown as three in number, by partitions I5 ilxed in and extending longitudinally between the transverse partitions II, I3, the partitions I5 being spaced laterally from the sides 5. 8 of the casing and each other, and providing the chamber with the three passes P, P' and P. The partitions are of the same width and oi' a width less than the width of the casing between the walls "I, 8 and spaced from said walls thereby providing passes P3, P4 at opposite sides of the casing open to and connecting the passes P, P and Pz in communication with each other through said passes P3 and P4.

'I'he pass P* has an inlet at the top and a side of the casing for the air to be heated and the air pass P3 has an outlet Il for the heated air arranged at the bottom and side of the casing opposite the air inlet I 6. The passes P, P and P2 are oi.' successively less width, the pass P being of least width and the pass P2 of greatest width.

A plurality of series or sections of ducts in the form of tubes are provided, and shown as three in number; one section T extends longitudinally of the air pass P, another section T extends longitudinally of the air pass P and another.

section T3 extends longitudinally of the air pass P, the tubes at one end being secured in openings in the partition I3 and opening to the outlet chamber C2, and secured at the opposite ends in openings in the partition II and opening to the portions C, C of the hopper bottom at the opposite end of the casing with the section of tubes T in `communication with the gas inlet to the portion C and the other sections T and T2 in communication with the portion C and connected in communication with each other at said end through the portion C'.

By the arrangement of the air inlet I6 and the air outlet II the air to be heated is caused to iiow through the passes and traverse the ducts or tubes in a direction reverse to the ilow oi the waste gases of combustion through the ducts or tubes.

The air to be heated is caused to pass through one of the air passes between partitions I5 and traverse the tubes in said pass, such as the air pass P2, should the load on the boiler furnace be low and thus assure the heating of the air to a relatively high temperature, thel air ilowing from the inlet to the outlet in the direction indicated by the arrows b shown in Figure 3. Should the boiler furnace be under a high load the air is caused to flow through all of the passes between the partitions I5, the air flowing as indicated by the arrows c from the inlet I8 through the passes P, P and P and from the latter pass through the passes P4 and P1I to the outlet II. For this purpose adjustable arranged in the passes P:I and P4 to extend longitudinally and transversely thereof. the one 'partition Il being pivotally supported at a longitudinal edge portion at the end oi.' the partition between the passes P' and P2, as at 2li, and the other partition I 9 pivotally supported at a longitudinal edge portion at the end of the partition between the passes P and P', In the position shown in full lines in Figure 3 the air passes successively through the passes P, P3 and P and from the latter through the passes P, P2 to the outlet II. To cause the air flowing through the inlet Ii to only traverse the ducts in air pass P, the adjustable partition I9 is adjusted to the dot and dash line position I5' `shutting of! the air pass P from the inlet and the adjustable partition Il shuting oii the outlet from the air passes P and P' from the air pass P3. In some instances while the boiler furnace is operating under high load it may be desirable not to heat the air to a very high temperature. In this case the air may be caused to traverse only the ducts or tubes in the air pass P arranged with the least number of ducts. For this purpose the partitions Il, I 9 are adjusted to the positions shownin Figure 4, the partition I 9 shutting on' the inlet from the pass P* and thereby cause the air to pass from the inlet through and traverse the ducts in the air pass P and flow from the pass P through the pass P3 directly to the outlet. l

The yadjustable partitions I8, I9 are adapted to be automatically actuated and the actuation thereof controlled by the temperature of the waste gases of combustion exiting from the air preheater to a stack S. For this purpose the pivot support of the partitions Il, I9 are connected to actuating means, as shown in a conventional manner at 22 in Figure 1 connected to the pivot support 2| of the partition I9, and said means actuated and the actuation thereof controlled by a. temperature responsive element attached to the stack and said actuating means, as shown in a conventional manner at 23 in Figure 1.

To cause the waste gases of combustion to pass or ow only through the section or series of tubes T in the air pass P2 when the boiler furnace is operating under low load, and cause said gases to pass through all of the duct sections T, T and T2 when the boiler furnace is operated under high load, an adjustable partition 24 is arranged in the gas outlet chamber Cz to extend transversely thereof, the partition being connected to a pivot support 25 extending longitudinally thereof and parallelly of and at the end of the partition between the air passes P, P. To cause the gases to pass through all oi partitions Il, I! are amasar the sections of the tubes T, T' and Ta when the boiler furnace is operating under high load the 'through the section of tubes T', and from said latter tubes into the portion C oi the hopper y bottom and then reversely through the tubes 'Il'2 to the outlet I4 and thence to the stack S. When the boiler furnace is operating under low load the partition 24 is adjusted to the position shown in dotted lines 24' extending transversely of the ends. of the section of the tubes T lopening to the chamber C?, the gases flowing from the tubes T through the chamber C2 to the outlet I'4. The

'partition 24 is adapted to be actuated automatically and the actuation thereof controlled by the temperatures of the gases of combustion exiting through the stack S, and actuated in synchronism with the actuation of the adjustable partition I9, for which purpose the pivot support of the partition 24 is connected to actuating means, such as 22 shown in connection with the partition I9, and the actuation thereof controlled by a temperature responsive element, such as 33,

attached to the stack S and the actuating means 22.

The outlet for the gases may have a natural draft connection with. the stack S through a conduit 26 or the flow of the gases through the tubes or ducts of the air preheater to the stack may be induced as by a fan F the outlet of which is connected to a stack and the inlet connected to the conduit 26 to connect the inlet of the fan with the outlet I4 for the gases from the chamber C2 of the air preheater. The conduit 26 has a regulatable connection with the stack, shown as a damper 21, which is adjusted to shut off the Aconduit 26 from the stack when the flow of the gases is induced by the fan F.

To separate foreign substances from the gases, such as soot, fLv ash and the like before the gases exit to the stack S a separator is interposed in the connection of the fan with the gas outlet I4, and shown as of the centrifugal type consisting of a body 28 having a hopper bottom and a conduit 29 extended centrally into the top of the body to substantially midway the top and bottomland in eieet constituting a continuation of the conduit 26. Inlet means 30 to the body is connectedv to the outlet I4 of the air preheater for the exit gases, said inlet means being arranged to cause the gases admitted into the body of the separator to swirl about the outlet conduit 29 thereby causing particles of foreign substances to separate from the gases and dropto the hopper bottom of the separator bottom, the gases passing upwardly to the conduit 29 either through the fan as indicated by the arrows, or through the conduit 26 lto the stack S. I

It will be obvious that various modifications may be made in the construction and arrangef ment of the parts without departing from the scope of the invention and that portions of the invention may be used without others and come within the scope offthe invention.

Having described my invention, I claim:

l. Means for heating air by waste gases of ccmbustion, comprising a rectangular casing having an inlet for the gases at the bottom and a side thereof and an outlet for the gases at the top in the opposite side thereof and an inlet at the top and an end thereof and an outlet at the bottom and opposite end for the air to be heated.

a plurality of sections of ducts extending longitudinally of the casing, one section being in communication with the gas inlet, adjustable means* operative in one position of adjustment to cause .the gases to pass through the section of the ducts in communication with the gas inlet directly to the gas outlet and in another position of adjustment cause the gases to pass in series through vall of the duct sections to the gas outlet, and adjustable means operative in one position of adjustment to cause the air to traverse transversely and lengthwise of one section of ducts from the air inlet to the air outlet and in another position of adjustment cause the airito traverse trans-v versely and longitudinally in series all of the sec-k tions of ducts from the air inlet to the air outlet.

2. In means for heating air by waste gases of combustion, a rectangular casing havingl transverse partitions arranging said casing with a chamber at the top and bottom of the casing and a chamber intermediate said chambers, said v bottom chamber being separated into a pair of compartments and one compartment having an inlet for' the gases of combustion at one side of let for said gases at the opposite side of the casing, conducting tubes for the passage of gases exthe casing, and the.top chamber having an outf with the other compartment in said bottom chamber, and adjustable means in the chamber having the outlet forthe gases operative in one position of adjustment to cause the gases to pass through the tubes in communication with the gas inlet chamber directly to the gas outlet, and in another position of adjustment cause thegases passing from said tubes to flow reversely through an adjacent series of the tubes into the other compartment in the chamber, and thence from said compartment ow reversely through another series of the tubes to the gas outlet, and the intermediate chamber having an air inlet to the top thereof at one end of the casing and an air outlet from the bottom of said chamber through the opposite end of the casing and cause the air to be heated to traverse transversely and longitudinally of the tubes from the air inlet to the air outlet.

3. In means for heating air by hot waste gases of combustion, a rectangular casing, transverse plates arranging the casing with achamber at the top and bottom of the casing and a chamber intermediate said chambers extending longitudinally for the greater portion of the casing and the bottom chamber separated into two compartments, one compartment having an inlet at a passes at the opposite ends thereof and a series of three passes at right angles to andopen for the entire length at the opposite sides to said end passes, tubes extending longitudinally through each of the passes between said partitions secured at the ends in openings in the u other arranging the intermediate chamber with transverse partitions connecting all of said tubes at one end in communication with the top chamber, and connecting the section of tubes in one pass in communication with the bottom compartment having the inlet for the gases and connecting said ends of the tubes in the other passes in communication with the other compartment in said bottom chamber, an adjustable partition in the chamber at the top of the casing adapted in one position of adjustment to cause the gases owing through the section of tubes in communication with the inlet for the gases .to flow from said tubes directly to the outlet of said top chamber, and in another position of adjustment cause the gases'to ow reversely in series through the sections of tubes in the successive passes to the gas outlet from the top chamber and said casing having an inlet for the air to be heated to the top of an kend pass in the intermediate chamber and an outlet for the heated air from the bottom of the other end pass in the intermediate chamber to cause the air to traverse transversely and lengthwise of the tubes in the passage of the air through the intermediate chamber from the air inlet to the air outlet.

4. In means for heating air by waste products of combustion as claimed in claim 3, adjustable partitions in the end passes of the intermediate chamber `in the casing adapted to be adjusted to cause the air to traverse the tubes in either one of two of the passes between the partitions in the ow of the air from the inlet to the outlet, or to cause the air to flow in series through all of said passes and traverse the tubes therein to the outlet, and thermostatically operative means actuated by the temperature of the gases existing from the outlet for thegases to adjust the partition.

5. In means for heating air by hot waste gases of combustion as claimed in claim 3, adjustable partitions in the end passes of the intermediate chamber in the casing adapted to be adjusted to cause the air to iiow from the air inlet through and traverse the tubes in one pass between the partitions to the outlet and to cause the air to flow in series through and traverse the tubes inail of the passes between the partitions to the outlet.

6. In means for heating air by waste gases of combustion as claimed in claim 3, adjustable partitions in the end passes in the intermediate chamber operative in one position of adjustment to cause the air to traverse the tubes in either one of the end passes in the iiow of the air from the inlet to the outlet of said chamber, and in another position of adjustment of said partitions cause the air to flow from the inlet in series through all of the passes and traverse the tubes therein to the outlet.

7. In means for heating air by waste gases of combustion as claimed in claim 2, wherein the means in the chamber having the outlet for the gases to cause the gases to pass through one or all of the sections of the tubes in series comprises an adjustable partition in said chamber, and thermostatieally operated means actuated by the temperature of the gases exiting from the outlet of said chamber connected to and operative to adjust the partition.

8. In apparatus for heating air by Waste gases of combustion, a rectangular casing having a chamber at the bottom and arranged with a pair of compartments and one compartment having an inlet for the gases of combustion, a chamber at the top end of the casing having an outlet for said gases, and an intermediate'chamber having4 an' air inlet to one side and upper portion vof.

said chamber and an outlet from the opposite side and bottom portion of said chamber, tubes extending through the intermediate chamber connected in communication with the top and bottom chambers of the casing with a section of said tubes in communication with the compartment of the lower chamber having the inlet for the waste gases of combustion, adjustable means in the gas outlet chamber operative in one position to cause the' gases flowing from the section of the tubes in communication with the gas inlet to flow from the upper chamber to the outlet thereof and in another position cause the gases to flow in series through successive sections of the tubes to the gas outlet,means to arrange the intermediate chamber with multiple passes, and adjustable means operative in one position to cause the air to pass from the air inlet through one pass and transversely and longitudinally traverse the tubes therein to the outlet and in another position cause the air to pass through another of the passes and transversely and longitudinally traverse the tubes therein to the outlet, and in another position thereof cause the air to pass in series through and transversely and longitudinally traverse the tubes in all of the paes to the outlet.

9.`In apparatus for heating air by waste gases of combustion, a casing arranged with a chamber at the bottom having an inlet for the hot gases of combustion, a chamber at the top having an outlet for said gases and an intermediate chamber, fixed partitions extending longitudinally oand spaced laterally from each other in the intermediate chamber and of less width than the width of the casing arranging said chamber with a series of three passes between said partitions and passes at the opposite ends of said passes, one of said passes constituting an air ,inlet pass having an inlet opening to the upper portion thereof at a side of the casing and the other pass constituting an air outlet pass having an outlet opening from the lower portion thereof at the side of the casing opposite the side with the air inlet opening,V a partition in the air inlet pass pivotally mounted at a longitudinal edge in line with the partition separating an end pass from the intermediate pass of the series of passes, said partition being of a length and width equal to the length and width of said inlet pass and adapted in one position to extend transversely of the inlet pass and cause the air to pass from the air inlet through said end pass of the series ofA passes to the outlet pass., and in another position of adjustment shut ci said end pass of the series of passes from the inlet and cause the airlto pass through the other end pass of the series of passes to the outlet pass, and a partition in the air outlet pass pivotally mounted at a longitudinal edge in line with the partition separating the other end pass from the intermediate pass of the series of passes, said partition being of a length and width cqual to the length and width of the outlet pass and adapted in one position thereof to extend transversely of the outlet pass and cause the air flowing from the one end pass of the series of passes into the outlet pass to iiow reversely through the intermediate pass of the series of passes into the inlet pass and thence through the other end pass of the series of passes to the outlet pass, and in another position thereof permit the air flowing from the one end pass into the outlet pass to ow directly through the outlet pass to the other` through the other compartment of said bottom chamber, and an adjustable partition in the top chamber operative in one position of adjustment to cause the gases to pass from the tubes Yin communication with the gas inlet directly to the gas outlet and in another position of adjustment cause the gases to flow reverseiy in series through the tubes in the successive passes to the gas outlet.

GERHARD NIEMITZ. 

